Hi silva, I reviewed your pictures, and on consideration, the tiny bit of print that the original FETs are attached to would only provide next to zero heat dissipation. The absence of heat discolouration bears this out. As they're mounted on the print side of the board, they're probably subjected to more external heat from the rear of the display panel, than internal operational heat, so I shouldn't worry about it too much.
If in doubt, run the TV for a substantial period, then feel the FETs for temperature level.If they appear to be overheating, perhaps you can fashion a heatsink for them out of aluminium, or use a strip of heat transfer rubber they seem to use widely these days, between the board and panel.
Bruce